Circuits having switchable or selectable capacitance are used in various applications. For example, a voltage-controlled oscillator (VCO) may include a capacitor bank comprising a number of switched capacitance cells or units electrically connected in parallel with each other. The switched capacitance cells may be individually switchable or selectable. A selected subset of the capacitance cells provides the VCO with capacitance to achieve a desired oscillation frequency. A VCO may be used in radio frequency (RF) transmitter or receiver circuitry. In a RF transmitter or receiver, rapid tuning or changing of operating frequency may be desirable.